The present invention relates to a burner, particularly a ceramic burner for use in the combustion shaft of a hot-blast stove, of the type including concentric chambers for the combustion media, e.g. combustion air and gas, which chambers are joined at an opening area of the combustion shaft, and a mixing element arranged centrally within such opening area.
Especially in hot-blast stoves having large dimensions, and which therefore are acted upon by large volumes of combustion media, it is extremely difficult to control the mixing of combustion air and combustion gas. This is particularly true since it is not possible to avoid variations in the burner load produced by variations in the heating value of the supply of combustion gas. Defective mixing as a preliminary stage for combustion again leads to an irregular combustion. There results an unstable burning which results in abnormal stresses, chiefly on the combustion shaft. When mixing is totally insufficient, combustion takes place in the form of constantly repeating explosion-type ignitions having distinct pressure amplitudes and oscillation periods. The burner pulsates noticeably. Such pulsation is propagated to the various parts of the hot-blast stove installations, e.g. the pipeline systems, and may produce considerable damage thereto.
German published application DT-OS No. 1,551,828/24c,10 discloses a hot-blast stove burner wherein the flow rate and the direction of flow of air and combustion gas are adjustably controlled in an attempt to secure an extensive mixing effect. Regulation is effected by means of an inner cone that is displaceable in the vertical direction, thereby widening the flow through the central burner chamber in an annular manner, and that is introduced into a similarly annular flow through an outer burner chamber. This arrangement does not however result in mixing and distribution of the air and combustion gas through the entire cross section of the combustion shaft at the opening of large volume hot-blast stove burners.